1. Field of the Invention
The invention relates to a surface cleaning apparatus that fluid cleaning system to deliver heated cleaning fluid to a surface to be cleaned. In one of its aspects, the invention relates to a surface cleaning apparatus that has an inline heater to heat cleaning fluid.
2. Description of the Related Art
Extractors are well-known devices for deep cleaning carpets and other fabric surfaces, such as upholstery. Most carpet extractors comprise a fluid delivery system and a fluid recovery system. The fluid delivery system typically includes one or more fluid supply tanks for storing a supply of cleaning fluid, a fluid distributor for applying the cleaning fluid to the surface to be cleaned, and a fluid supply conduit for delivering the cleaning fluid from the fluid supply tank to the fluid distributor. The fluid recovery system usually comprises a recovery tank, a nozzle adjacent the surface to be cleaned and in fluid communication with the recovery tank through a working air conduit, and a source of suction in fluid communication with the working air conduit to draw the cleaning fluid from the surface to be cleaned and through the nozzle and the working air conduit to the recovery tank. An example of an extractor is disclosed in commonly assigned U.S. Pat. No. 6,131,237 to Kasper et al., which is incorporated herein by reference in its entirety. The Kasper et al. '237 includes an aluminum body that includes a cover made of aluminum and further includes a fluid inlet fitting and a fluid outlet fitting connected to the metal body for circulating fluid through the metal body. Corrosion may be a problem resulting from casting the fluid inlet and fluid outlet fittings into the metal heater block. This problem might be overcome the use screw-in fittings with an O-ring rather than casting the fittings into the block. This solution may reduce the corrosion problem but may also add significant cost in that the block is required to be tapped and a hand assembly is required for threading the fittings into the tapped holes. Further, the metal cover may have to be Teflon coated to avoid corrosion problems.
The U.S. Patent Application Publication No. 2004/0197095 to Thweatt, Jr. discloses a heater for fluids including a housing made of non-metallic material and having an internal cavity and an inlet and an outlet in fluid communication with the internal cavity. The heater housing is made of a polymeric material. A heating element is suspended within the cavity for heating fluid flowing therethrough. Further, the heating element comprises a U-shaped portion and electrical connectors at opposite ends of the heating element which extend through the housing. Thweatt, Jr. '095 has fluid inlet and outlet fittings mounted to the heating element in an end wall of the plastic housing. The heating element may melt the walls of the plastic housing when the housing is dry, regardless of the existence of a thermal cutoff control.